A known image reading apparatus includes a reader configured to read an image on a first side of a first medium at a first position, and to read an image on a first side of a second medium, which is different in thickness from the first medium, at a second position. The reader is urged by an urging member to the first position. Contact of the second medium with the reader causes the reader to move from the first position to the second position. When the second medium loses contact with the reader, the reader moves back to the first position from the second position due to an urging force of the urging member.